1. Field
Embodiments of the present disclosure relate to a voltage converter, and more particularly, to a voltage converter which controls an output voltage in a digital manner.
2. Description of the Related Art
FIG. 1 is a circuit diagram of a conventional voltage converter.
The conventional voltage converter includes a power supply circuit 20 and a power supply control circuit 10. The power supply circuit 20 generates an output voltage VOUT based on an input voltage VIN provided from a power supply such as a battery, and provides the output voltage VOUT to a load circuit 30. The power supply control circuit 10 controls the power supply circuit 20 using the output voltage VOUT that is fed back thereto. That is, the power supply control circuit 10 feedback-controls the power supply circuit 20.
The power supply circuit 20 of FIG. 1 includes a buck converter circuit which is controlled by a control signal VPWM to generate the output voltage VOUT based on the input voltage VIN. The output voltage VOUT of the power supply circuit 20 has a triangular waveform so that a voltage level of the output voltage VOUT oscillates around a reference voltage VREF.
The power supply control circuit 10 includes a comparator 11 and a frequency adjustor 12. The comparator 11 compares the output voltage VOUT to a reference voltage VREF and generates a comparison signal VCMP, and the frequency adjustor 12 adjusts a frequency of the comparison signal VCMP according to the reference signal VF and outputs the control signal VPWM.
In the conventional voltage converter shown in FIG. 1, when the output voltage VOUT changes, the frequency of the control signal VPWM output from the power supply control circuit 10 may be changed and thus electromagnetic interference (EMI) noise may result in a system including the voltage converter.